Silver Spring, MD to Philadelphia, PA buses and trains from $21

Or, see buses and trains from Philadelphia, PA to Silver Spring, MD.
Here are some trips other travelers have found on Routefriend.
$21
4h 40m
1 stop
Greyhound
$21
3h 25m
0 stops
Greyhound
$21
5h 40m
2 stops
Greyhound
$23
6h 35m
2 stops
Greyhound Megabus
$44
3h 1m
1 stop
Greyhound Amtrak
$55
1h 58m
1 stop
Greyhound Amtrak
$61
4h 24m
2 stops
Greyhound Amtrak